Diamond ring



FIG. 1 is an end elevational view of a diamond ring showing my new design, the opposite end being the same;

FIG. 2 is a top plan view thereof;

FIG. 3 is a side elevational view thereof, the opposite side being the same; and

FIG. 4 is a bottom plan view thereof. 

The ornamental design for a diamond ring, substantially as shown and described. 